One Hundred and Fifty Years of Warming on Caribbean Coral Reefs
Colleen B. Bove1,2*, Laura Mudge1,3, and John F. Bruno1
1 The Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3280 USA
2 The Department of Biology, Boston University, Boston, Massachusetts, 02215 USA
3 Integral Consulting Inc., Annapolis, Maryland 21401 USA
*Corresponding author: colleenbove@gmail.com
Abstract:
Abstract text will go here
Citation:
Citation will go here
Caribbean Ecoregion Coral Reefs
Figure 1
## OGR data source with driver: ESRI Shapefile
## Source: "/Users/colleen/Dropbox/Git/CaribbeanSST/data/EcoRegions", layer: "Caribbean_ecoregions"
## with 17 features
## It has 9 fields
Caribbean coral reef site locations and ecoregion designation. The colour of each reef represents the designated ecoregion (Spalding et al. 2010) and n denotes the number of unique reefs within that ecoregion.
SST Extraction and Analysis
Figure 2
Historic SST trend on Caribbean coral reefs (1871–2020). Long-term SST records (HadISST) on Caribbean coral reefs depicting A) mean monthly SST each year (represented by line colour: blue to red) and B) GAM smoothed annual mean SST time (black line), annual maximum (red line), and annual minimum (blue line) SST. The grey dashed horizontal line denotes the overall mean SST for all sites over the entire period (27.3 °C) and the grey ribbon represents the 95% confidence interval around the true annual SST mean through time.
Figure 3
Historic SST trends on coral reefs within ecoregions (1871–2019). Long-term SST records (HadISST) on Caribbean coral reefs separated by ecoregion depicting GAM smoothed annual mean SST time (black line), annual maximum (red line), and annual minimum (blue line) SST. The grey dashed horizontal line denotes the mean SST over the entire period and the grey ribbon represents the 95% confidence interval around the true annual SST mean for each ecoregion.
Figure S2
Historic SST trend on Caribbean coral reefs (1871–2020). Long-term SST records (HadISST) on Caribbean coral reefs depicting significant changes in warming rate based on the first derivative of the GAM modelled slope. The GAM smoothed annual mean SST time is represented by the black line with significantly positive (red) or negative (blue) identified over the curve. The most recent significant warming event began in 1987 and is highlighted in the yellow box. The annual maximum (red line) and annual minimum (blue line) SST are also depicted, along with the overall mean SST for all sites over the entire period (27.3 °C; grey dashed line). The grey ribbon represents the 95% confidence interval around the true annual SST mean through time.
Figure S3
Historic SST records (1981-2019; Pathfinder) on Caribbean coral reefs depicting A) mean monthly SST each year (represented by line colour: blue to red) and B) GAM smoothed annual mean SST time (black line), annual maximum (red line), and annual minimum (blue line) SST. The grey dashed horizontal line denotes the overall mean SST for all sites over the entire period (27.23 °C) and the grey ribbon represents the 95% confidence interval around the true annual SST mean through time.
Figure S4
Comparison of HadISST (1871-2020) and Pathfinder (1981-2019) SST recorded on Caribbean coral reef locations. The high-resolution Pathfinder is represented as darker data over the long-term HadISST. Both datasets are represented by GAM smoothed annual mean SST time (solid line), annual maximum (red line), and annual minimum (blue line) SST. The dashed horizontal line denotes the overall mean SST for all sites over the entire period and the grey ribbon represents the 95% confidence interval around the true annual SST mean through time.
Figure S5
Historic SST trends on coral reefs within Caribbean ecoregions (1871 - 2020) with corresponding reef locations (see Figures 1, 3 in the main text). The colour of each reef location and box around long-term SST (HadISST) plots represent the designated ecoregion. Plots depict SST data with GAM smoothed annual mean SST time (black line), annual maximum (red line), and annual minimum (blue line) SST. The grey dashed horizontal line denotes the mean SST over the entire period and the grey ribbon represents the 95% confidence interval around the true annual SST mean for the A) Bahamian, B) Eastern Caribbean, C) Floridian, D) Greater Antilles, E) Gulf of Mexico, F) Southern Caribbean, G) Southwestern Caribbean, and H) Western Caribbean ecoregions.
HadISST GIF
Long-term SST records (HadISST) on Caribbean coral reefs depicting mean monthly SST each year (represented by line colour: blue to red).
Caribbean Basin Maps and Marine Heatwaves
Figure 4
All Marine Heatwave analyses were performed by Laura Mudge (GitHub: Lmudge13) Laura's code/analyses are included in this script and identified within code chunks when pulled or modified from her original work.
Warming patterns throughout the Caribbean Sea. Increasing warming events across the Caribbean depicted through A) rate of SST change (°C per decade) from 1981 to 2019 (Pathfinder; mean slope 0.23 ± 0.087 °C per decade) and B) increasing marine heatwave events (slope of counts per year). Grey ocean area was not included in these analyses.
Figure 5
##
## Call:
## glm(formula = total_events ~ year, family = poisson(link = "log"),
## data = mhw_pixel %>% filter(!is.na(total_events)))
##
## Deviance Residuals:
## Min 1Q Median 3Q Max
## -3.1341 -1.5133 -0.3252 0.7218 5.3058
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -93.153736 0.892226 -104.4 <2e-16 ***
## year 0.046973 0.000445 105.6 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## (Dispersion parameter for poisson family taken to be 1)
##
## Null deviance: 53904 on 20333 degrees of freedom
## Residual deviance: 41900 on 20332 degrees of freedom
## AIC: 84987
##
## Number of Fisher Scoring iterations: 5| Frequency | ||||
|---|---|---|---|---|
| Predictors | Log-Mean | std. Error | Statistic | p |
| (Intercept) | -93.15 | 0.89 | -104.41 | <0.001 |
| year | 0.05 | 0.00 | 105.56 | <0.001 |
| R2 Nagelkerke | 0.480 | |||
##
## Call:
## lm(formula = log(avg_duration) ~ year, data = mhw_pixel %>% filter(!is.na(avg_duration)))
##
## Residuals:
## Min 1Q Median 3Q Max
## -0.94040 -0.31030 -0.04558 0.25596 2.63499
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) -3.651e+01 6.663e-01 -54.79 <2e-16 ***
## year 1.935e-02 3.328e-04 58.16 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 0.4391 on 14879 degrees of freedom
## Multiple R-squared: 0.1852, Adjusted R-squared: 0.1852
## F-statistic: 3382 on 1 and 14879 DF, p-value: < 2.2e-16| Duration | ||||
|---|---|---|---|---|
| Predictors | Estimates | std. Error | Statistic | p |
| (Intercept) | -36.51 | 0.67 | -54.79 | <0.001 |
| year | 0.02 | 0.00 | 58.16 | <0.001 |
| R2 / R2 adjusted | 0.185 / 0.185 | |||
##
## Call:
## lm(formula = log(avg_rt) ~ year, data = mhw_pixel %>% filter(!is.na(avg_rt)))
##
## Residuals:
## Min 1Q Median 3Q Max
## -4.3348 -0.6973 -0.0082 0.7152 3.2591
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 87.9680923 1.6676413 52.75 <2e-16 ***
## year -0.0414970 0.0008326 -49.84 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 1.021 on 14334 degrees of freedom
## Multiple R-squared: 0.1477, Adjusted R-squared: 0.1476
## F-statistic: 2484 on 1 and 14334 DF, p-value: < 2.2e-16| Return Time | ||||
|---|---|---|---|---|
| Predictors | Estimates | std. Error | Statistic | p |
| (Intercept) | 87.97 | 1.67 | 52.75 | <0.001 |
| year | -0.04 | 0.00 | -49.84 | <0.001 |
| R2 / R2 adjusted | 0.148 / 0.148 | |||
Figure S6
Significance of A) rate of SST change (°C per decade) and B) number of marine heatwave events per year across the Caribbean depicted in Figure 4. Grey ocean area was not included in these analyses.
Figure S7
A) Rate of SST change (°C per decade) over the duration of the HadISST database across the Caribbean from 1871 to 2020 (mean slope 0.04 ± 0.014 °C per decade) and B) significance of rate of SST change. Grey ocean area was not included in these analyses.
Figure S8
A) Rate of SST change (°C per decade) across the Caribbean from 1981 to 2020 (HadISST; mean slope 0.17 ± 0.046 °C per decade) and B) significance of rate of SST change. Grey ocean area was not included in these analyses.
Figure S9
## Call:
## Model: total_events ~ year | NULL
## Data: mhw_pixel %>% filter(!is.na(total_events))
##
## Coefficients:
## (Intercept)
## Estimate Std. Error t value Pr(>|t|)
## Bahamian -183.6279 7.275158 -25.24040 1.953138e-138
## Eastern Caribbean -265.1574 7.936654 -33.40921 2.742567e-238
## Floridian -265.6125 12.895065 -20.59799 2.568514e-93
## Greater Antilles -233.2420 5.019797 -46.46444 0.000000e+00
## Gulf of Mexico -182.1729 13.768136 -13.23148 8.436490e-40
## Southern Caribbean -243.3208 10.922736 -22.27655 1.245185e-108
## Southwestern Caribbean -257.2126 8.216807 -31.30323 4.045844e-210
## Western Caribbean -122.1500 8.114225 -15.05382 6.135744e-51
## year
## Estimate Std. Error t value Pr(>|t|)
## Bahamian 0.09312266 0.003637977 25.59738 2.920963e-142
## Eastern Caribbean 0.13363943 0.003968283 33.67689 5.496137e-242
## Floridian 0.13429635 0.006448317 20.82658 2.462474e-95
## Greater Antilles 0.11788449 0.002510151 46.96310 0.000000e+00
## Gulf of Mexico 0.09242105 0.006885203 13.42314 6.612073e-41
## Southern Caribbean 0.12286688 0.005462416 22.49314 1.086922e-110
## Southwestern Caribbean 0.12991043 0.004108298 31.62147 2.860042e-214
## Western Caribbean 0.06227124 0.004057718 15.34637 7.415730e-53
##
## Residual standard error: 2.183396 on 20318 degrees of freedom## Call:
## Model: log(avg_duration) ~ year | NULL
## Data: mhw_pixel %>% filter(!is.na(avg_duration))
##
## Coefficients:
## (Intercept)
## Estimate Std. Error t value Pr(>|t|)
## Bahamian -23.19844 1.577364 -14.707095 1.274500e-48
## Eastern Caribbean -62.00352 2.144389 -28.914300 6.769992e-179
## Floridian -15.98585 2.827260 -5.654185 1.594671e-08
## Greater Antilles -41.10983 1.169384 -35.155122 3.787737e-260
## Gulf of Mexico -24.61235 2.981547 -8.254892 1.647233e-16
## Southern Caribbean -44.12879 2.541903 -17.360530 7.487656e-67
## Southwestern Caribbean -46.24434 1.946378 -23.759170 1.676450e-122
## Western Caribbean -19.31153 1.762539 -10.956650 7.889006e-28
## year
## Estimate Std. Error t value Pr(>|t|)
## Bahamian 0.012701250 0.0007883091 16.112018 6.496100e-58
## Eastern Caribbean 0.032136225 0.0010697045 30.042153 1.491411e-192
## Floridian 0.009100136 0.0014126027 6.442106 1.214508e-10
## Greater Antilles 0.021648359 0.0005840316 37.067105 9.808347e-288
## Gulf of Mexico 0.013433658 0.0014898782 9.016616 2.172990e-19
## Southern Caribbean 0.023174546 0.0012692754 18.258091 1.137606e-73
## Southwestern Caribbean 0.024210345 0.0009716811 24.915937 2.797166e-134
## Western Caribbean 0.010708486 0.0008809193 12.156035 7.711994e-34
##
## Residual standard error: 0.4292549 on 14865 degrees of freedom## Call:
## Model: log(avg_rt) ~ year | NULL
## Data: mhw_pixel %>% filter(!is.na(avg_rt))
##
## Coefficients:
## (Intercept)
## Estimate Std. Error t value Pr(>|t|)
## Bahamian 59.88498 3.925165 15.256677 3.819296e-52
## Eastern Caribbean 160.56762 5.771956 27.818582 6.418356e-166
## Floridian 94.89711 7.068327 13.425681 7.552162e-41
## Greater Antilles 96.47683 2.968519 32.499987 1.282883e-223
## Gulf of Mexico 74.64287 7.429697 10.046556 1.139551e-23
## Southern Caribbean 100.82897 6.476988 15.567263 3.376862e-54
## Southwestern Caribbean 110.34842 4.984973 22.136212 8.680499e-107
## Western Caribbean 43.38395 4.385126 9.893433 5.268285e-23
## year
## Estimate Std. Error t value Pr(>|t|)
## Bahamian -0.02747928 0.001960998 -14.012910 2.549683e-44
## Eastern Caribbean -0.07767442 0.002877847 -26.990466 1.529541e-156
## Floridian -0.04499755 0.003530407 -12.745711 5.232704e-37
## Greater Antilles -0.04575364 0.001481981 -30.873302 1.113797e-202
## Gulf of Mexico -0.03483787 0.003711432 -9.386637 7.111510e-21
## Southern Caribbean -0.04791523 0.003232834 -14.821432 2.470539e-49
## Southwestern Caribbean -0.05265035 0.002487611 -21.165024 6.303556e-98
## Western Caribbean -0.01920103 0.002190962 -8.763743 2.098388e-18
##
## Residual standard error: 1.00861 on 14320 degrees of freedom
MHW trends (1981 - 2018) across Caribbean coral reefs by ecoregion. Temperature data are based on OISST gridded data to determine frequency (number events per year), duration (number days per event), return time (number days per event) since the previous event, onset rate (°C per day) from start until peak intensity, peak intensity (°C), and total days reefs experience MHWs per year. Points denote annual mean values (±SD) and blue lines represent linear (lm or glm) trends within each ecoregion (see Figures 1, S5 for ecoregion locations). Frequency, duration, and return time across all Caribbean coral reefs are depicted in Figure 5 in the main text.
Supplemental Tables
Table S1
Table S1. Marine heatwave properties examined in this study
| Metric | Units | Description |
|---|---|---|
| Frequency | Number of events | Number of discrete mhw events |
| Total MHW days | days | The total number of days a location experienced a MHW per year |
| Duration | days | The number of days between the start and end date of each distinct MHW event |
| Peak intensity | °C | The maximum temperature, above the seasonal varying climatological mean, reached during the MHW event |
| Onset rate | °C per day | “Rate of temperature change between onset date and date of peak intensity” |
| Return time | days | The number of days elapsed since a previous mhw event in that location |
Table S2
Table S2. Calculated warming rates from both HadISST and Pathfinder databases for different temporal ranges.
| Temperature parameter | HadISST (1871-2020) | HadISST (1981-2020) | HadISST (1987-2020) | Pathfinder (1981-2019) | Pathfinder (1987-2019) |
|---|---|---|---|---|---|
| Caribbean Basin (°C per decade) | 0.04 | 0.17 | 0.18 | 0.23 | NA |
| Caribbean Basin (total °C for period) | 0.60 | 0.68 | 0.61 | 0.90 | NA |
| Caribbean Reefs (°C per decade) | 0.04 | 0.15 | 0.16 | 0.19 | 0.2 |
| Caribbean Reefs (total °C for period) | 0.60 | 0.60 | 0.54 | 0.74 | 0.66 |
Table S3
Table S3. Mean ocean warming rate (°C per decade; with 95% confidence interval) and total increase in temperature (°C) on coral reefs within each Caribbean ecoregion since the noted year of inflection point. The inflection point for each ecoregion was identified as the year in which annual warming rates noticeably increased based on the GAM smoothed annual means (see Figures 3 and S4). Years indicated with an asterisk (*) represent inflection points identified for ecoregions that occurred before the Pathfinder dataset record, therefore those rates and total warming values were calculated from the beginning of the record in 1981.
| Ecoregion | Inflection point | Mean rate (°C per decade) | Lower confidence interval | Upper confidence interval | Warming extent (°C) |
|---|---|---|---|---|---|
| Bahamian | 1988 | 0.17 | 0.161 | 0.182 | 0.53 |
| Eastern Caribbean | 1984 | 0.26 | 0.260 | 0.267 | 0.91 |
| Floridian | 1993 | 0.22 | 0.207 | 0.231 | 0.57 |
| Greater Antilles | 1986 | 0.16 | 0.160 | 0.168 | 0.53 |
| Gulf of Mexico | 1981 | 0.21 | 0.186 | 0.241 | 0.80 |
| Southern Caribbean | 1981 | 0.26 | 0.258 | 0.268 | 0.99 |
| Southwestern Caribbean | 1982 | 0.20 | 0.194 | 0.204 | 0.74 |
| Western Caribbean | 1999 | 0.24 | 0.235 | 0.253 | 0.48 |
Table S4
Table S4. Model results for MHW trends in the Caribbean basin between 1981-2018. Frequency and duration modeled using glm model with poisson distribution and log link. Estimates, standard error, z scores, and p-values are reported. Nagelkerke pseudo r-squared used to assess goodness of fit. MHW intensity was log transformed before modeling with ols model. Estimate, standard error, t value and p-value are reported along with multiple and adjusted r-squared.
| Estimate | Standard error | Statistic | P-value | |
|---|---|---|---|---|
| Frequency | ||||
| (Intercept) | -93.154 | 0.892 | -104.406 | < 0.001 |
| year | 0.047 | 0.000 | 105.559 | < 0.001 |
| R2 | 0.480 | |||
| Duration | ||||
| (Intercept) | -36.508 | 0.666 | -54.790 | < 0.001 |
| year | 0.019 | 0.000 | 58.157 | < 0.001 |
| R2 | 0.185 | |||
| Return Time | ||||
| (Intercept) | 87.968 | 1.668 | 52.750 | < 0.001 |
| year | -0.041 | 0.001 | -49.840 | < 0.001 |
| R2 | 0.148 | |||
Session information
All code was written by Colleen B. Bove, feel free to contact with questions.
Session information from the last run date on 2021-04-07:
## R version 3.6.3 (2020-02-29)
## Platform: x86_64-apple-darwin15.6.0 (64-bit)
## Running under: macOS High Sierra 10.13.6
##
## Matrix products: default
## BLAS: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRblas.0.dylib
## LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib
##
## locale:
## [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
##
## attached base packages:
## [1] splines grid stats graphics grDevices utils datasets
## [8] methods base
##
## other attached packages:
## [1] transformr_0.1.3 fmsb_0.7.0 performance_0.7.0
## [4] modelr_0.1.8 broom_0.7.5 sjPlot_2.8.7
## [7] ggpubr_0.4.0 gridExtra_2.3 repmis_0.5
## [10] kableExtra_1.3.4 plotly_4.9.3 foreach_1.5.1
## [13] mgcv_1.8-31 nlme_3.1-152 Hmisc_4.5-0
## [16] Formula_1.2-4 survival_3.1-8 lattice_0.20-41
## [19] gganimate_1.0.7 fields_11.6 spam_2.6-0
## [22] dotCall64_1.0-1 binr_1.1 gapminder_0.3.0
## [25] gifski_1.4.3 RColorBrewer_1.1-2 xts_0.12.1
## [28] zoo_1.8-9 rnaturalearth_0.1.0 forcats_0.5.1
## [31] stringr_1.4.0 dplyr_1.0.5 purrr_0.3.4
## [34] readr_1.4.0 tidyr_1.1.3 tibble_3.1.0
## [37] tidyverse_1.3.0 rgdal_1.5-23 maptools_1.1-1
## [40] viridis_0.5.1 viridisLite_0.3.0 raster_3.4-5
## [43] sp_1.4-5 ggrepel_0.9.1 ggplot2_3.3.3
## [46] ncdf4_1.17 sf_0.9-8
##
## loaded via a namespace (and not attached):
## [1] utf8_1.2.1 R.utils_2.10.1 tidyselect_1.1.0
## [4] lme4_1.1-26 htmlwidgets_1.5.3 lpSolve_5.6.15
## [7] munsell_0.5.0 codetools_0.2-16 effectsize_0.4.4
## [10] units_0.7-1 statmod_1.4.35 withr_2.4.1
## [13] colorspace_2.0-0 highr_0.8 knitr_1.31
## [16] rstudioapi_0.13 ggsignif_0.6.1 labeling_0.4.2
## [19] emmeans_1.5.5-1 rnaturalearthdata_0.1.0 farver_2.1.0
## [22] coda_0.19-4 vctrs_0.3.7 generics_0.1.0
## [25] xfun_0.22 R6_2.5.0 assertthat_0.2.1
## [28] scales_1.1.1 nnet_7.3-12 rgeos_0.5-5
## [31] gtable_0.3.0 rlang_0.4.10 systemfonts_1.0.1
## [34] rstatix_0.7.0 lazyeval_0.2.2 checkmate_2.0.0
## [37] yaml_2.2.1 abind_1.4-5 crosstalk_1.1.1
## [40] backports_1.2.1 tools_3.6.3 ellipsis_0.3.1
## [43] jquerylib_0.1.3 proxy_0.4-25 Rcpp_1.0.6
## [46] plyr_1.8.6 base64enc_0.1-3 progress_1.2.2
## [49] classInt_0.4-3 prettyunits_1.1.1 rpart_4.1-15
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